שכפול באאוקריוטים

DNA replication in eukaryotic chromosomes initiates at multiple origins of replication, which are identified and bound by the origin recognition complex, or ORC.

The ORC then recruits helicases to unwind the DNA, producing a replication bubble with two replication forks.

The two forks move in opposite directions and disrupt the nucleosomes ahead of them. These nucleosomes are then reassembled on the daughter strands, maintaining the chromatin structure.

At each fork, RNA primers provide the site for DNA polymerase to elongate the leading strand and the Okazaki fragments of the lagging strand.

An RNase enzyme then removes these primers, and the DNA polymerase fills the gaps. Finally, DNA ligase seals the fragments together.

However, as the last primer is removed from the lagging strand at the end of the linear chromosome, it produces an overhanging stretch of the template DNA.

An enzyme called telomerase extends this overhanging stretch with non-coding DNA to prevent the loss of coding DNA during subsequent replication cycles.

The replication continues until the adjacent replication bubbles merge and the whole chromosome is duplicated.